Re: [bug report] nvme not re-recognize when changed M.2 SSD in S3 mode

[Lukas Wunner <lukas@xxxxxxxxx>]

On Wed, Apr 10, 2024 at 12:07:40PM +0200, Lukas Wunner wrote:
> --- a/drivers/pci/hotplug/pciehp_core.c
> +++ b/drivers/pci/hotplug/pciehp_core.c
> @@ -152,6 +152,25 @@ static int get_adapter_status(struct hotplug_slot *hotplug_slot, u8 *value)
>  	return 0;
>  }
>  
> +static bool pciehp_device_replaced(struct controller *ctrl)
> +{
> +	struct pci_dev *pdev;

I've realized this needs to be

+	struct pci_dev *pdev __free(pci_dev_put);

to avoid leaking a ref on the child device.  For testing purposes,
the patch should still be fine without this change, but I'll have to
fix this up if/when submitting a proper patch.

> +	u32 reg;
> +
> +	pdev = pci_get_slot(ctrl->pcie->port->subordinate, PCI_DEVFN(0, 0));
> +	if (!pdev)
> +		return true;
> +
> +	if (!pci_bus_read_dev_vendor_id(ctrl->pcie->port->subordinate,
> +					PCI_DEVFN(0, 0), &reg, 0))
> +		return true;
> +
> +	if (reg != (pdev->vendor | (pdev->device << 16)))
> +		return true;
> +
> +	return false;
> +}
> +
>  /**
>   * pciehp_check_presence() - synthesize event if presence has changed
>   * @ctrl: controller to check
> @@ -172,7 +191,8 @@ static void pciehp_check_presence(struct controller *ctrl)
>  
>  	occupied = pciehp_card_present_or_link_active(ctrl);
>  	if ((occupied > 0 && (ctrl->state == OFF_STATE ||
> -			  ctrl->state == BLINKINGON_STATE)) ||
> +			      ctrl->state == BLINKINGON_STATE ||
> +			      pciehp_device_replaced(ctrl))) ||
>  	    (!occupied && (ctrl->state == ON_STATE ||
>  			   ctrl->state == BLINKINGOFF_STATE)))
>  		pciehp_request(ctrl, PCI_EXP_SLTSTA_PDC);